Work on membrane proteins from human and animal lenses has continued. Changes of the lens membrane constituents have been studied during cataract development. An in vitro model system using glucose deprived incubated lenses mimics many of the changes observed with cataract formation in vivo. Changes in membrane proteins as well as enzyme inactivation can be followed with the system. Tissue culture of lens epithelial cells is being refined. Characterization of a defined culture medium for optimal growth of human and animal lens cells has been undertaken. The isolation of the Na-K ATPase inhibitor present in cultured lens cells from the Nakano mouse has also been carried out.